Oh, if self-reported then it's pretty useless, yes.
I recall someone arriving on Mumsnet to gloat that, less than a year into transition, they had kicked up a huge ruckus to force Center Parcs to allow them to use the open, communal, women's only changing rooms for the spa. They'd been offered use of the unisex cubicle area instead, but had felt this was discriminatory; as they felt they were a woman, they wanted the right to undress amongst the undressing women, communally. There was absolutely no interest or concern in how the women might feel. None. When Mumsnetters carefully explained that many women will be acutely uncomfortable getting undressed alongside a male body they do not know, and that those women have not consented, and that some women may well have suffered sexual assault, so that could retraumatise them, the empathetic, compassionate response was, "you are obsessed with my body..." Women wanting privacy from all male people in vulnerable situations, and wanting this male person to change elsewhere to facilitate that, was reframed in this person's own mental landscape as an obsession with them, individually.
This person then reported the thread to the police as a hate incident.
Apparently, a male choosing to come and tell a group of women that they had succeeded in forcing a company to allow access to all their women customers while they and that male person were naked, and that group of women pointing out that a male person - whose gender identity is necessarily both subjective and invisible - would distress and alarm them when they were unclothed, and that they did not consent to this, is a hate incident. And now recorded as such in the data, because hate incidents are unquestioningly accepted on the word of the complainant. There is no test. Purely subjective. So women telling a male person that no, they didn't consent - women wanting their own rights under the Equality Act upheld, in fact - is recorded as hate.
I do, as I said earlier, think trans people will be subject to harm and harassment, and this is obviously wholly unacceptable. I also think self reporting in this instance is likely to be pretty worthless. Making such stats absolutely meaningless, really.